Herbicidal method

ABSTRACT

Herbicidal compositions comprising an effective amount of at least one compound of the formula   WHEREIN X is selected from the group consisting of hydrogen and lower alkyl of one to six carbon atoms when Y is selected from the group consisting of bromine and chlorine and when Y is hydrogen, X is selected from the group consisting of chlorine, bromine and lower alkyl of one to six carbon atoms and n is 1, 2 or 3 and to a method of killing plants.

United States Patent i 1 Perronnet et al.

[ 1 Apr. 2, I974 I54I HERBICIDAL METHOD [75 l Inventors: ,lacouesPerronnet; Plerre Cirauit,

[2i] Appl. No.: I30,852

[30] Foreign Application Priority Dita Sept. I7, 1970 France 70.33715 [52] U.S.CI. ..7I/l2l [5i] Int. CI....... AOIn 9/20 [58] Field oi Selrch 260/566 B. 424/327,

7I/I2l [56] Relerences Cited UNITED STATES PATENTS 3,305,347 2II967 Minieri 7I/i2i FOREIGN PATENTS OR APPLICATIONS 6,903,247 9II970 Netherlands l.455,835 9/1966 France OTHER PUBLICATIONS German Patent 1,909,868, Chem Abat. J0l72,

Primary Examiner-Lewis Gotts Assistant Examiner-Catherine L. Mills Attorney, Agent, or Firm-Hammond & Littcll 57 ABSTRACT Herbicidal compositions comprising an effective amount of at least one compound of the formula wherein X is selected from the group consisting of hydrogen and lower alkyl of one to six carbon atoms when Y is selected from the group consisting of bromine and chlorine and when Y is hydrogen, X is selected from the group consisting of chlorine, bromine and lower alkyl of one to six carbon atoms and n is l, 2 or 3 and to a method of killing plants.

4 Claims, No Drawing:

HERBICIDAL METHOD STATE OF THE ART Netherland Pat. application Ser. No. 69-03247 describes ltydrazines of the formula wherein X and Y are halogen, nitro or alkyl, m is to and p is 0 to 3 with the sum of m p being at most equal to 6 and their use as insecticides.

OBJECTS OF THE INVENTION THE lNVENTlON The novel herbicidal compositions of the invention are comprised of an effective amount of at least one compound of the formula wherein X is selected from the group consisting of hydrogen and lower alkyl ofone to six carbon atoms when Y is selected from the group consisting of bromine and chlorine and when Y is hydrogen. X is selected from the group consisting of chlorine, bromine and lower alkyl of one to six carbon atoms and n is l, 2 or 3 and an inert carrier. The compositions may also contain one or more other pesticidal agents.

The compositions may be in the form of powders, granules, suspensions, emulsions, or solutions containing, for example, other active principles, cationic, nonionic, or anionic surface active agents, inert powders such as talc, clay, silicates, kieselguhr. etc, a vehicle such as water. alcohol, hydrocarbons or other organic solvents, animal, vegetable or mineral oils, etc.

An example of a specific composition in the form of a emulsifiable concentrate is l0 percent by weight of N-(a-chloro-4'-methyl-benzylidene)-4-chlorophenylhydrazine, 6 percent by weight of Atlox 485l (alkylaryl sulfonatc mixed with a polyoxyethylene triglyceride with a viscosity of 300-700 cps at C, soluble in water), 4 percent by weight of Atlox 4855 (alkylaryl sulfonate mixed with a polyoxyethylene triglyceride with a viscosity of 1,500 to 1,900 cps at 25C, dispersihle in water), percent by weight of cyclohexanone and 40 percent by weight of xylene. The composi' tions generally contain 5 to 80 percent, preferably l0 to percent, by weight of the active compounds of formula I.

Particularly preferred compounds of formula I are N- (rx-chloro-3'-chloro-hcnzylidene)-phcnylhydrazine, N-

2 (or-chloro-benzylidene)-4-chloro-phenylhydrazine, N- (or-chloro-4'-mcthyl-benzylidenc)-4-chlorophenylhydrazine and N-((I-ChiOl'U-bCnZylldCl'lC)-2,4,(\- trichloro-phenylhydrazine.

The herbicidal properties of the compoundsof formula l have been shown in tests with plants of a great number of botanical families such as wheat. oats, corn. vulpin of the grass family, Chrysanthemum of the composacae family, flax of the linaceae family, mustard of the cruciferaceac family. clover of the papilionaceac family and beets of the chenopodiaceae family.

The novel method of the invention for killing plants comprises contacting plants with a herbicidal amount of at least one compound of formula I. The compounds can be applied in any conventional manner but are preferably employed as post-emergence by spraying or other suitable means. The usual dosage is 0.5 to 10 kg per ha.

The compounds of formula I may be prepared by reacting in the presence of a tertiary base a phenylhydrazine of the formula Qua-Na.

XQLC' wherein X has the above definition to obtain a henzyhydrazide of the formula Ill and reacting the latter with first a chlorination agent and then phenol to obtain the corresponding com pound of formula I.

The condensation of the benzoyl chloride of formula IV with the phenylhydrazine of formula III is preferably effected in the presence of pyridine. The preferred chlorination agent is phosphorus pentachloride although phosphorus oxychloride or a mixture of phosphorus oxychloride and phosphorus pentachloride can also be used. The chlorination reaction may be effected in an organic solvent such as ethyl ether or isopropyl ether or in the absence of a solvent.

The reaction of the benzyhydrazide of formula V with phosphorus pentachloride results in the formation of a dichlorophosphinyl phenylhydrazone of the formula which when reacted with phenol results in the corresponding hydrazone of formula l.

N-(u-chloro-benzylidene)-2.4.(r-trichloropheuylhydrazine may be prepared by reacting the phenylhydrazone ol' benzaldehyde with chlorine. preferably in art organic solvent such as ethyl acetate.

The pheuylhydrazines of formula lll are described in the literature or can be made by known processes. For. instance. phcnylhydrazine is described in Beilstein. Vol. l5. p. 67'. l. p. 23'. ll. p. 44; 4-chlorophenylhydrazinc is described in Beilstcin. Vol. l5, p. 425'. l. p. 106; II. p. 150 and 2.4.6-trichlorohenylhydrazine is described in llcilstein. Vol. l5, p. I34; l. p. 3 l ll. p. 57. The phenylhydrazone of benzaldehyde is described in Bcilstein. Vol. l5. p. 134; l. p. 3 l; ll. p. 57.

The benzoyl chlorides of formula IV are described in the literature or can be made by known processes. For example. 4-methylbenzoylchloride is described in Beilstein. Vol. 9, p. 486; l. p. I93. ll, p. 329 and 3- chlorobenzoyl chloride is described in Beilstein. Vol. 9. p. 338'. l. p. 139; ii. p. 224.

In the following examples there are described several preferred embodiments to illustrate the invention. However, it should he understood that the invention is not intended to be limited to the specific embodiments.

EXAMPLE I N-(a-chloro-4'-methyl-benzylidenel-4-chlorophenylhydrazine STEP A: B-(4'-chlorophenyl)-4- mcthyl-bcnzhydrazide 100 g of 4-chloro-phenylhydrazine were added to 500 ml of pyridine and then ll3 g of 4-methyl-ben7.oyl

chloride was added thereto at 5C. The mixture was stirred for In hours at C and the reaction mixture was then poured into a icewater mixture. The precipitate formed was recovered by vacuum filtration, was washed and then dried to obtain l54 g of (344'- chlorophenyl)-4-methyl-benzhydrazide melting at 2ltlC. A sample of the product melted at 218C after crystallization from ethanol.

Analysis (',,ll,.('lN,t). molecular wclghl 260.72

20C and then cooled at 0C. A mixture of I20 g oiphenol and l2() cc ofethyl ether was added thereto and the mixture was stirred for IS minutes at 0C and then poured into 400 ml of methanol. The mixture was stirred for l hour at 20C and the ether was distilled off. After cooling to it"t', crystallilation was allowed and the crystals formed were recovered by vacuum filtration. The product was washed with iced methanol and dried to obtain 73 g ol N-(rx-chloro-4' methylbenzylidene)-4-chloro-phcnylhydrazine melting at ll7C. Crystallization from acetonitrile did not change the melting point.

Analysis: ll (l,N,; molecular wcIght 27! I7 Calcu- '1- (10.22 '5' H 4.1] (125.40 'X N ltl U-t luted Found: Mitt 4.2 25 3 It! 1 As far as is known. this product is not described in the literature EXAMPLE ll N-(a-chloro-3'-chloro-beuzylidenc)-phenylhydrazine Using the procedure olStep A of Example l. phenylhydrazine and 3-chlorobenzoyl chloride were reacted to obtain fl-phenyl-3-chloro-benzhydrazide melting at 164C. The latter is then reacted with phosphorus pentachloride as in Step B of Example I to obtain N-(ochloro-3-chloro-benzylidenc)-phenylhydrazine melting at 76C.

As far as is known. both the final hydrazone and the benzhydrazide are not described in the literature.

EXAMPLE lll N-(a'chloro-benzylidencl-4-chloro-phenylhydrazine Using the procedure of Steps A and B ol Example I; 4-chloro-phenylhydrazine and ben'loyl chloride are reacted to obtain B-(4-chlorophenyl)-benzhydrazide melting at l54C which is then reacted with phosphorus pentachloride to obtain N-tu-chloro-benzylidene 4-chloro-phenylhydrazine melting at ll2C.

EXAMPLE lV N-(a-chloro-benzylidene)'2.4.(rtrichlorophenylhydrazine Using the procedure of Steps A and B of Example I. bcn'myl chloride and 2.4.6trichloro-phenylhydrazine were reacted to form [3-(2.4.b-trichlorophenyl benzhydrazide melting at t6oC which was reacted with phosphorus pentachloride to form N-(wchlorobenzylidene)-2,4,o-trichloro-phenylhydrazine melting at 97C.

EXAMPLE V 50 g of the phenylhydrazone ol' benzaldehyde in (rtlt) ml of ethyl acetate was cooled to 8C and a current of chlorine was bubbled through the solution at a temperature below 15C for 45 minutes. The mixture was cooled to 5C and the precipitate formed was recovered by vacuum filtration and was dried to obtain ()0 g of N-(a-chloro-benzylidene)-2,4.6trichlorophcnylhydrazine melting at 97C. The said product is described by Humphries et al. [Soc. 1925. p. 1304].

POST-EMERGENCF. HERBlClDAl, ACTIVITY The nine vegetables used in this study were cultivated in a cultivation flat (23 X 14 X 4 cm) having a double bottom and watered from below. The nine species were planted. using 20 grains per species. in spaced rows of 3 cm in a single flat and 4 flats were used for each concentration. The culture conditions were as follows: 20 i 2C temperature; about percent humidity; lighting by fluorescent tube (daylight bright light) for o to 22 hours each day. The soil mixture was comprised of ill volumes of normal dirt. volumes of river sand and 2 volumes of peat moss. The treatment was effected after 2l days on the above ground part of the plants. The test products were applied under standard conditions with a microsprayer at doses of 5. 2.5, 1.25. 0.6kglha at a dilution corresponding to 560 liters per ha. The same procedure was followed without spraying to obtain controls for the test. The final results were determined from the weight of the plants days after the post-emergence spray treatment and are expressed as a percentage of reduction of vegetation P.

P weight of control plants-weight of treat plants/weight of control plants X I00 A, N(n-chloro-3'-ehluro-benzylidene) phenylhydrulinc Doses in kl per ha 5 2.5 L 0.6 ()ttltt I00 I00 I 00 I00 Wheat I 00 I 00 90 90 Corn 75 75 6O 40 Vulpine I00 100 75 to Heels I00 I00 I00 I00 Chrysanthemum I00 I00 I00 I00 Flax I00 I00 I00 I00 MUlIlH-I I00 I00 I00 I00 ('Invet I ()0 I00 I00 I00 TABLE II II, N-(a-chloro-4methyl-benlylidene)A-chloro-phcnylhydruzine Danes in Itg per ha 5 2.5 l.25 0.6 ()all I00 I00 I00 75 Wheat I00 I00 I00 I00 Corn 40 I5 20 5 Vulpine I00 70 70 20 llcctst I00 I00 I00 I00 (ihryllnthcmum I00 I00 [(X) I00 Fla! I00 I00 I00 I00 Mustard I00 I00 I00 I00 Clover I00 I ()0 I 00 I00 TABLE III C. N-(a-chloro-benzylidenc)-2,4.6-trichlom-phenylhydrulne Dtuca in It; per ha 5 2.5 [.25 (Ht Oat: )0 75 50 40 TABLE II I Continued C. N-(a-chloro'benzyIidene) -2.4.fi-trichloro-phenylhydntzine Doses in kg per ha Wheat Corn Vulpine Beets Chrysanthemum Flu Mustard Clover The said Tables show that the tested compounds have a remarkable post-emergence herbicidal activity against the plants tested. However. it should be noted that compound 8 and especially compound C are relatively safe for the corn.

Various modifications of the compositions and method of the invention may be made without depart ing from the spirit or scope thereof and it should he understood that the invention is to be limited only as defined in the appended claims.

We claim:

I. A post-emergence method of killing plants which comprises contacting plants with a herbicidal amount of at least one phenylhydrazone of the formula D gg wherein when Y is hydrogen. X is lower alkyl of one to six carbon atoms and when Y is selected from the group consisting of chlorine and bromine. X is selected from the group consisting of hydrogen and lower alkyl of one to six carbon atoms and n is l, 2 or 3.

2. The method of claim I wherein the phenylhydrazone is N-(a-chIoro-4'-methyI-benzylidenc)-4-chlorophenylhydrazine.

3. The method of claim I wherein the phenylhydrazone is N-(a-chloro-benzylidene)-4-chlorophenylhydrazinc.

4. The method of claim I wherein the phenylhydrazone is N-(a-chloro-benzylidene)-2.4,o-trichlorophenylhydrazine.

. O I l 0 

2. The method of claim 1 wherein the phenylhydrazone is N-( Alpha -chloro-4''-methyl-benzylidene)-4-chloro-phenylhydrazine.
 3. The method of claim 1 wherein the phenylhydrazone is N-( Alpha -chloro-benzylidene)-4-chloro-phenylhydrazine.
 4. The method of claim 1 wherein the phenylhydrazone is N-( Alpha -chloro-benzylidenE)-2,4,6-trichloro-phenylhydrazine. 